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Unformatted text preview: What is the efficiency ? Problem 47 Brushless DC Operation from a Current Source Consider the machine in Problem 46, with the same load torque. Instead of being supplied from a voltage source, consider the situation if the machine is supplied from a current source (with all the current in the qaxis). Plot the rms current, rms voltage, and efficiency of the machine as the speed is varied from 0 to 4000 RPM. Problem 48 Brushless DC Parameter Identification A threephase brushless dc machine is open circuited, and is spun using a dynamometer. The a to b phase voltage measured from an oscilloscope if found to be sinusoidal. The waveform has a peaktopeak voltage of 200 V, and a frequency of 82 Hz. What is m ?...
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 Spring '08
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